This invention relates generally to systems that identify program segments broadcast by radio, television, or cable broadcasters and specifically to systems that identify and verify the integrity of the program segments, e.g., commercial advertisements or entire programs, using a superimposed frame of encoded data.
Commercial broadcast systems get their name, in part, due to the presence of commercials. Although distasteful to many, commercials are essential for television and radio broadcasters to generate the vast majority of their income. Even cable systems, which originally earned their reputations as being commercial-free alternatives, have quickly followed suit due to the significant income potential. Commercials provide name recognition to advertisers, enabling them to sell more of their products, and aid the advertisers to quickly generate a demand for new products and to test new marketing approaches. Thus, commercials have a substantial value to both the broadcasters and the advertisers.
Advertisers are willing to pay sizable sums of money only if broadcasters timely and completely broadcast their commercials. Many reasons exist for the advertiser's strict demands. For instance, an advertiser might be doing a time-limited sales campaign. If a particular commercial was broadcast after the end of such a sales campaign, this broadcast probably would be useless. Advertisers also target certain audiences and will pay significant premiums for a commercial broadcast within a program that captures a desired group of viewers. Thus, time or date shifting is not acceptable for a commercial. Additionally, commercials are carefully composed to be watched (or at least shown) in their entirety. Thus, a truncated broadcast of a commercial or one with audio or video dropouts is potentially useless.
Despite all well-intentioned efforts, commercials are sometimes broadcast at a wrong time, truncated, or broadcast with dropouts or other degradations. To receive payments from the advertisers, broadcasters generally must certify that each advertiser's commercial was timely and completely broadcast. Currently, this certification is manually performed.
Many attempts have been made to automate the identification of various program segments such as commercials. An ideal system would identify any and all program segments and correlate them with the appropriate advertisers without requiring any pre-processing efforts by either the advertisers or the broadcasters. Also, an ideal system would not alter or degrade the audio or video signals associated with each program segment. Such a system would need to correlate vast amounts of video and/or audio data to recognize each particular program segment.
Consequentially, such a system would also be highly susceptible to video or audio noise that intermittently could cause it to fail to recognize a program segment. Also, since the processing and storage requirements for such a system would be astronomical, such systems are not believed to be currently commercially feasible. Some systems have attempted to minimize these requirements by inserting cue sequences into the program segment to forewarn pattern recognition circuitry. Such a cue might be a blank video frame or a peculiar type of fade sequence. This type of alteration to the content of a program segment generally is not desirable.
Other systems have approached this task by encoding data within the video lines of the program segment. These systems generally use a particular line within the vertical blanking interval and thus outside the viewable image. Since these systems require high frequency processing and precise timing to encode and decode this data, they are not believed to have been commercially successful. Additionally, since these systems require a video channel, they can be used only with television and not radio broadcasters.
Other systems have combined modulated data with the audio channel of the program segment. Some of these systems have notched out sections of the audio channel within the range of human hearing and FSK-encoded data using audible frequencies with amplitudes that are substantially inaudible to the typical listener. In one system, a subaudible (below the nominal frequency range of human hearing) frequency band was chosen to encode the identification data and on-off keying of a fixed modulation frequency was used to designate the binary data content. Such a system is believed to have an undesirable amount of noise susceptibility, because it is not possible to differentiate between the absence of a modulation frequency and an off-keyed modulation state.
As previously discussed, program segments, in addition to not being broadcast at the proper time, might be truncated. It is still desirable to recognize a program segment, even when truncated. However, if a data encoding system required the full duration of the program segment to communicate the program segment's identity and duration, such a system would be too susceptible to errors.
It should therefore be appreciated that a need exists for a practical and thus marketable system to encode data onto the audio channel of a program segment with an encoding technique that is acceptably immune to noise and program segment truncations such that the system can still identify the program segment and determine its duration despite audio dropouts and program segment truncations. The present invention satisfies these needs.